Central heating and cooling systems have been considered a integral component of our homes and businesses for many, many years. Often times little thought is put into the type of system that gets installed. Most central heating systems currently installed create heat by combustion, more often than not the combustion of a fossil fuel, just as they did over a hundred years ago. In recent years the proliferation of central air conditioners to cool our spaces has imposed a further burden on our already taxed electricity system. More advanced, non-combustion technologies operate not by burning a fuel but simply by transferring or moving heat from location to another.
Non-combustion or heat transfer systems include:
- earth energy systems (ground-source heat pumps / GeoExchange)
- solar thermal water heaters
- solar thermal air heaters
- advanced biomass combusters .
Each of these technologies are briefly described below.
Earth Energy Systems
Earth energy involves tapping into the solar energy naturally stored in your own backyard. The Earth absorbs almost 50% of all solar energy and no matter where you live, the underground temperature stays relatively constant all year. Ground-source heat pump and GeoExchange systems harness this relatively constant, renewable energy source, and use it for heating, air conditioning and hot water.
During the winter, the systems absorb heat from the ground and uses it to warm the air in your home. In the warmer summer months, the processed is reversed, taking heat from your home and transfers it back into the ground.
The Canadian Renewable Energy Network reports that Canada has more than 30,000 earth energy installations in use for residential, commercial, institutional and industrial applications. Earth energy is used widely in northern Europe, especially in the Scandinavian countries, which have adopted the technology quickly. Earth energy is becoming more common in the southern United States where it's used to cool buildings.
Ground Source Heat Pumps / GeoExchange Systems
A ground-source heat pump (GSHP) or GeoExchange system uses a refrigeration cycle to move heat between the indoors and outdoors. Instead of moving heat to and from outdoor air, a ground-source heat pump uses the soil. GSHPs can heat and cool the home and heat domestic water.
A ground source heat pump uses the soil or ground water or both as sources of heat in the winter, and as the "sink" for heat removed from the home in the summer. For this reason, ground source heat pump systems have come to be known as earth-energy systems (EESs). Heat is removed from the earth through a liquid, such as ground water or an antifreeze solution, upgraded by the heat pump, and transferred to indoor air. During summer months, the process is reversed: heat is extracted from indoor air and transferred to the earth through the ground water or antifreeze solution.
A GSHP has two parts: a circuit of underground piping outside the house, and a heat pump unit inside the house.
The outdoor piping system can be either an open system or closed-loop. An open system takes advantage of the heat retained in an underground body of water. The water is drawn up through a well directly to the heat exchanger, where its heat is extracted. The water is discharged either to an above-ground body of water, such as a stream or pond, or back to the underground water body through a separate well.
Closed-loop systems collect heat from the ground by means of a continuous loop of piping buried underground. An antifreeze solution, which has been chilled by the heat pump's refrigeration system to several degrees colder than the outside soil, circulates through the piping, absorbing heat from the surrounding soil.
For more information about Earth Energy check out these links:
Solar Thermal Water Heaters
Every hour the amount of solar energy hitting the earth is greater than the amount of energy used by every human being on earth annually. Solar energy can be utilized as a source of heat, for example to heat your water, and as electricity, such as solar photovoltaics. Solar water heating systems are commonly referred to in the industry as Solar Domestic Hot Water (SDHW) systems.
A solar domestic hot water system uses the sun to heat water for home use. The SDHW system connects to a home's existing gas or electric water heating system, providing a supplemental source of heat for all hot water needs including showers, dishwashing, clothes washing,and cooking. Solar water heating systems are a proven technology that work well even in cold climates.
One of the most common questions on SDHW is whether or not Canada has enough sunlight to support solar applications such as water heating. Natural Resources Canada reports that there is enough solar energy to deliver an average of 2500 kWh of energy per year. This means that solar energy can provide enough hot water for approximately half of the hot water needs of a family of four.
SDHW systems provide numerous benefits over conventional water heaters, including reduced hot water heating costs and reduced greenhouse gas emmissions. The amount of savings,economic and environmental, depends on several factors such as the size of the collectors and storage tank, the efficiency of your appliances, your region's sunlight, and the amount of water you typically use.
The most common type of residential solar domestic hot water system installed in colder climates is a closed loop active system. Closed loop systems have a set amount of fluid (water or antifreeze mixture) traveling through the heating system. They are called "active" systems because they rely on circulating pumps to move the fluid through the system. In Canada, a system like this can provide about 50% of the water heating energy needs in a home.
A closed loop active solar water heater is made up of collectors, heat transfer fluid (water, alcohol, oils, etc), circulating pump, heat exchanger, and a storage tank. The sun heats the heat transfer fluid in the collector. The circulating pump brings the heated fluid into the home where the heat is transferred to the domestic water supply. The domestic hot water supply is held in a storage tank to be used when needed.
Hot water for a wide variety of commercial applications can be provided using solar water heaters. Some of the most common applications include hot water in apartment buildings, hospitals, car washes, laundry mats and recreation centres.
A commercial solar hot water system is essential the same as that used in a residential application except that the components of the system (ex. thermal storage, heat exchanges, and piping) are larger.
For more information about Solar Thermal Water Heating check out these links:
Solar Thermal Air Heaters
Advanced Biomass Combustion Systems